Testicular dose in prostate cancer radiotherapy: impact on impairment of fertility and hormonal function.

PURPOSE

To determine the dose received by the unshielded testicles during a course of 20-MV conventional external-beam radiotherapy for patients with localized prostate cancer. Critical evaluation of the potential impact on fertility and hormonal impairment in these patients according to the literature.

PATIENTS AND METHODS

The absolute dose received by the testicles of 20 randomly selected patients undergoing radiotherapy of prostate cancer was measured by on-line thermoluminescence dosimetry. Patients were treated in supine position with an immobilization cushion under their knees. A flexible tube, containing three calibrated thermoluminescence dosimeters (TLDs) was placed on top or underneath the testicle closest to the perineal region with a day-to-day alternation. The single dose to the planning target volume was 1.8 Gy. Ten subsequent testicle measurements were performed on each patient. The individual TLDs were then read out and the total absorbed dose was calculated.

RESULTS

The mean total dose (+/- standard deviation) measured in a series of 10 subsequent treatment days in all patients was 49 cGy (+/- 36 cGy). The calculated projected doses made on a standard series of 40 fractions of external-beam radiotherapy were 196 cGy (+/- 145 cGy). The results of this study are appraised with the available data in the literature.

CONCLUSION

The dose received by the unshielded testes can be assessed as a risk for permanent infertility and impairment of hormonal function in prostate cancer patients treated with external-beam radiotherapy.